You cannot upgrade a Windows-based operating system when you have Windows PowerShell 1.0 installed

When you try to upgrade the operating system on a computer that has Windows PowerShell 1.0 installed, the upgrade fails. Additionally, the Compatibility Check feature displays the following message:

To work around this problem, eliminate the Compatibility Check error. To do this, follow these steps:

1. Uninstall Windows PowerShell 1.0.
2. Perform the operating system upgrade again.
3. Reinstall Windows PowerShell 1.0.

How to uninstall Windows PowerShell 1.0

To uninstall Windows PowerShell 1.0, follow the steps that are appropriate to your operating system.

Windows Vista

1. Click Start, type appwiz.cpl in the Start Search box, and then press ENTER.
2. In the list of tasks, click View Installed Updates.
3. In the Uninstall an update list, right-click Windows PowerShell(TM) 1.0 (KB928439), and then click Uninstall.
4. Follow the instructions to uninstall Windows PowerShell 1.0.
   
   Note If you disable Windows PowerShell by using the Turn Windows Features on or off option, this does not satisfy the Compatibility Check process. You must uninstall Windows PowerShell.

Windows Server 2003

1. Click Start, click Run, type appwiz.cpl, and then click OK.
2. Click to select the Show updates check box.
3. In the Currently installed programs and updates list, find the entry for the hotfix that installed Windows PowerShell 1.0. Depending on the installation package that was used, this entry resembles one of the following:
   • Hotfix for Windows Server 2003 (KB926139)
   • Hotfix for Windows Server 2003 (KB926140)
   • Hotfix for Windows Server 2003 (KB926141)
4. Click the Windows PowerShell hotfix entry, and then click Remove.
5. Follow the instructions to uninstall the hotfix for Windows PowerShell 1.0.

Note By default, if Windows Server 2003 Service Pack 2 is installed on the system, PowerShell 1.0 cannot be uninstalled. To resolve this issue, follow these steps:

1. Follow the steps in the following Microsoft Knowledge Base (KB) article, 931941, to trust Windows PowerShell 1.0 that was introduced in KB926139:
   931941  (http://support.microsoft.com/kb/931941/ ) The Oobmig.exe tool is available to restore trust to out-of-band updates after you install Windows Server 2003 Service Pack 2
   Note You may have to restart the computer.
2. Check whether the update can be uninstalled by using Control Panel. If the update cannot be uninstalled in this manner, uninstall PowerShell manually from the following location:
   C:\WINNT\$NtUninstallKB926139$\spuninst\spuninst.exe
   Note You may have to restart the computer.

Windows XP

1. Click Start, click Run, type appwiz.cpl, and then click OK.
2. Click to select the Show updates check box.
3. In the Currently installed programs and updates list, click Windows PowerShell(TM) 1.0, and then click Remove.
4. Follow the instructions to uninstall Windows PowerShell 1.0.

Click one of the following links to reinstall Windows PowerShell 1.0, depending on the version of the operating system and on the language preference:

For more information about Windows PowerShell 1.0 English language installation packages for Windows Server 2003 and for Windows XP, click the following article number to view the article in the Microsoft Knowledge Base: For more information about the Windows PowerShell 1.0 localized installation package for Windows Server 2003 and for Windows XP, click the following article number to view the article in the Microsoft Knowledge Base: For more information about the Windows PowerShell 1.0 Multilingual User Interface (MUI) language pack for Windows Server 2003 and for Windows XP, click the following article number to view the article in the Microsoft Knowledge Base: For more information about the Windows PowerShell 1.0 installation package for Windows Vista, click the following article number to view the article in the Microsoft Knowledge Base: For more information about Windows PowerShell, visit the following Microsoft Web sites:

• Windows PowerShell
  http://www.microsoft.com/windowsserver2003/technologies/management/powershell/default.mspx (http://www.microsoft.com/windowsserver2003/technologies/management/powershell/default.mspx)
• Windows PowerShell Online Help
  http://technet.microsoft.com/en-us/library/bb978526.aspx (http://technet.microsoft.com/en-us/library/bb978526.aspx)
• Windows PowerShell blog
  http://blogs.msdn.com/powershell (http://blogs.msdn.com/powershell)
• Windows PowerShell discussion group
  http://www.microsoft.com/communities/newsgroups/list/en-us/default.aspx?dg=microsoft.public.windows.powershell (http://www.microsoft.com/communities/newsgroups/list/en-us/default.aspx?dg=microsoft.public.windows.powershell)
• Windows PowerShell SDK
  http://msdn2.microsoft.com/en-us/library/ms714469.aspx (http://msdn2.microsoft.com/en-us/library/ms714469.aspx)